Question 1

Which phase of the cell cycle is primarily responsible for DNA replication, and what is the main event that occurs during this phase?

Accepted Answer

S phase; DNA is duplicated

Question 2

During which phase of the cell cycle do most cells in the human body remain if they are not actively dividing, and what is a real-life example of a cell type that stays in this phase permanently?

Accepted Answer

G0 phase; neurons

Question 3

What is the correct sequence of events in the cell cycle for a cell that is actively dividing?

Accepted Answer

G1 → S → G2 → Mitotic phase

Question 4

Which of the following best describes the structure and function of histones in eukaryotic cells?

Accepted Answer

Histones are proteins that DNA winds around to form chromatin

Question 5

If a human cell has just completed the S phase, how many chromosomes and chromatids does it contain?

Accepted Answer

46 chromosomes and 92 chromatids

Question 6

Which process is responsible for the division of the cytoplasm, and what is the result of this process?

Accepted Answer

Cytokinesis; two new cells are formed

Question 7

A scientist observes a cell with visible chromosomes, each consisting of two sister chromatids joined at a centromere. Which phase is the cell most likely in?

Accepted Answer

Mitotic phase

Question 8

Which of the following statements about genes is correct?

Accepted Answer

Genes are short segments of DNA that code for one or more proteins

Question 9

If a mutation occurs during the S phase of the cell cycle, which cellular process is most directly affected?

Accepted Answer

DNA replication

Question 10

Which equation best represents the number of chromatids ($$C) in a $$human cell after DNA replication, given the number of chromosomes ($$n) is 46$$?

Accepted Answer

$$C = 2n$$

Question 11

A patient has a genetic disorder caused by a mutation in a single gene. Which of the following best describes the location and nature of this gene?

Accepted Answer

It is a segment of DNA located at a specific position on a chromosome

Question 12

Which of the following best explains why neurons do not regenerate after injury in adults?

Accepted Answer

They remain permanently in the G0 phase and cannot re-enter the cell cycle

Question 13

During which phase of the cell cycle does the cell grow the most, and what is the approximate duration of this phase?

Accepted Answer

G1 phase; 6–9 hours

Question 14

Which of the following is true regarding chromatin during interphase?

Accepted Answer

Chromatin is long, thin, and not visible under a microscope

Question 15

If a cell fails to duplicate its DNA during the S phase, what is the most likely consequence during mitosis?

Accepted Answer

The daughter cells will have incomplete or missing genetic material

Question 16

Which of the following best describes the relationship between chromosomes, chromatin, and genes?

Accepted Answer

Chromosomes are made of chromatin, which contains genes

Question 17

A researcher is studying a cell that has just completed cytokinesis. Which phase of the cell cycle will this cell enter next?

Accepted Answer

G1 phase

Question 18

Which of the following statements about the number of chromosomes in different species is correct?

Accepted Answer

The number of chromosomes varies by species; for example, humans have 46, blue whales have 44, and fruit flies have 8

Cell Reproduction and Differentiation: The Cell Cycle, DNA, and Chromosomes

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